This invention generally relates to high frequency electrodeless lamps and, more particularly, to such a lamp which is particularly adapted to be operated by a very efficient and compact radio fequency oscillator operating in Class E mode.
High frequency electrodeless (HFE) lamps have received considerable attention in recent years as a possible replacement for the standard household incandescent lamps which convert electricity into light in a relatively inefficient manner. Fluorescent lamps are efficient converters of electricity into light, but their cumbersome size and need for ballasting has limited their application in the household. HFE lamps, in contrast to the standard fluorescent lamps, can be fabricated in a relatively compact size.
Copending application Ser. No. 883,544, filed Mar. 6, 1978 by J. W. H. Justice, the present applicant, and M. D. Nahemow, and owned by the present assignee, discloses a magnetic core for an HFE lamp which includes a gap of non-magnetic material in order to stabilize the radio frequency at which the device operates and to suppress harmonics of the operating frequency. The self-oscillatory circuits used to energize the lamp operate in a Class A, B, or C mode, with Class B or C being preferred.
U.S. Pat. No. 4,017,764, dated Apr. 12, 1977 to Anderson, discloses an HFE lamp of the fluorescent type wherein a ferrite core is entirely contained within a phosphor-coated envelope.
U.S. Pat. No. 4,010,400, dated Mar. 1, 1977 to Hollister, discloses an HFE lamp which utilizes a ferrite core as a part of a tuned circuit output for a radio frequency energizing source.
U.S. Pat. No. 4,005,330, dated Jan. 25, 1977 to Glascock et al. discloses an HFE lamp which utilizes a ferrite core which is positioned exteriorly of the sealed lamp envelope but with the core operatively positioned in energy transferring relationship with respect to the sealed envelope.
U.S. Pat. No. 3,987,335, dated Oct. 19, 1976 to Anderson discloses an HFE lamp of the fluorescent type wherein a ferrite core is only partially contained within the phosphor coated envelope.
The IEEE Journal of Solid-State Circuits, Volume SC-10, No. 3, June 1975, pages 168-176, Article by Sokal et al., entitled, "Class E--A New Class of High-Efficiency Tuned Single Ended Switching Power Amplifiers", considers the design parameters for Class E oscillators. A similar discussion is set forth in "Electronics Design" 20, Sept. 27, 1977.